There are known methods for cleaning ferromagnetic chip from a lubricant-coolant by washing the chip in organic solvents, such as in benzine, alkaline washing solutions, or in a hot water under pressure (cf., A. V. Alekseenko "Sbor i pererabotka metallicheskoi struzhki", 1980, Moscow, the Mashinostroenie Publishers, pp. 31 and 32). One disadvantage of these prior art methods resides in high labour intensity and costs associated with consumption of expensive ingredients of the washing solution, as well as in the need to employ special facilities for neutralizing the used washing solution and treating the waste water. However, the capital expenditures and cost price of the end product are substantial, whereas the damage to the environment is not prevented.
There is also known a method for cleaning ferromagnetic chip from a lubricant-coolant (cf., A. V. Alekseenko "Sbor i pererabotka metallicheskoi struzhki", 1980, Moscow, the Mashinostroenie Publishers, pp. 31 to 33) in which the ferromagnetic chip is conveyed to a heating zone, the chip is heated, held at a preset temperature, and then the clean chip is removed.
The ferromagnetic chip is processed here a rotating drum-type furnace, heating of the chip being done by the products of combustion of kerosene to a temperature of 700.degree.-900.degree. C., and the chip is held at this temperature for a time period of between 5 and 6 minutes. Ingredients of the lubricant-coolant present in the chip burn out, after which the chip is discharged and conveyed for a subsequent treatment.
A disadvantage of this method is low efficiency of the process, and low cleaning quality of the processed chip, as it turns out to be fouled with charred products of combustion of the organic ingredients of the lubricant-coolant and contains a substantial amount of oxides (up to 10-12%). Another disadvantage is contamination of the environment with gaseous toxic products of combustion of the lubricant-coolant and kerosene used for heating the chip necessitating the use of special arrangements capable of absorbing such products but still low in efficiency.
There is further known an apparatus for cleaning ferromagnetic chip from a lubricant-coolant (cf., A. V. Alekseenko "Sbor i pererabotka metallicheskoi struzhki", 1980, Moscow, the Mashinostroenie Publishers, pp. 31 and 32). The apparatus includes a charging conveyer, a washing machine, and a discharge conveyer. In this apparatus the conveyer carrying the chip is passed through the washing chamber of the washing machine, where the chip is washed with hot water (90.degree.-95.degree. C.) under a pressure of 3-4 kgf/cm.sup.2 (0.3-0.4 MPa).
Then the chip is delivered to the conveyer outside the chamber to be conveyed to a drying chamber. A disadvantage inherent in this apparatus is that subsequent to cleaning chip of any size about 2% of the initial quantity of the lubricant-coolant tends to remain at the chip surface. In addition, chip cleaning in this apparatus is inefficient and labour intensive, accompanied by environmental pollution with substantial amounts of water containing ingredients of the initial lubricant-coolant.
Another known apparatus for cleaning ferromagnetic chip from a lubricant-coolant (cf., A. V. Alekseenko "Sbor i pererabotka metallicheskoi struzhki", 1980, Moscow, the Machinostroenie Publishers, pp. 31 to 33) comprising a heating arrangement having a casting with a heater, a chip charging means, and a chip discharge means. The chip is charged into the heating arrangement in the form of a rotatable drum-type furnace 1.6 m in diameter and 8 m in length. The chip is heated here by a flow of gas for 5-6 minutes. Uses as the fuel is kerosene. The heating temperature is 700.degree.-900.degree. C. From the furnace the chip falls to the discharge means to be conveyed for further treatment. A major disadvantage of this prior art furnace is low efficiency caused by labour intensive charging and discharge procedures, and long chip cleaning process. In addition, the chip cleaned of grease in this apparatus shows high state of oxidation (10-12%), and has a film of charred products of combustion of organic compounds. Finally, substantial losses of water and oil present in the lubricant-coolant are in evidence in this apparatus. As much as 50 kg of water and 2.5 kg of oil are wasted per one ton of chip cleaned.
One more disadvantage is that the apparatus pollutes the environment with gaseous toxic products of combustion of organic compounds of the lubricant-coolant, as the facilities for absorbing these products are inefficient.
It is an object of the present invention to ensure a higher quality of cleaning ferromagnetic chip.
Another object is to prevent pollution of the environment with gaseous toxic products of combustion of ingredients of the lubricant-coolant.
One more object is to increase the efficiency of the chip cleaning process.
The objects of the invention are attained by that in a method for cleaning ferromagnetic chip from a lubricant-coolant in which the chip is conveyed to a heating zone, heated, held at a preset temperature, and the clean chip is discharged, according to the invention, in the course of heating and holding the chip is acted upon by a rotating electromagnetic field, the heating and holding being done within a temperature range from 105.degree. C. to 310.degree. C.
Preferably, the chip is heated and held at the preset temperature for a period of time 1.1 to 4.0 minutes.
Advisably, the chip is heated and held at the preset temperature in a flow of gas for a period of time from 0.7 to 3.1 minutes.
Carrying out the proposed method for cleaning ferromagnetic chip from a lubricant-coolant in a manner described heretofore makes it possible to avoid oxidation of the chip and ensure high chip cleaning quality thanks to the brief cleaning procedure at relatively low temperatures.
The objects of the invention are further attained by that in an apparatus for carrying out the method of cleaning ferromagnetic chip from a lubricant-coolant comprising a heating arrangement having a casing with a heater, a chip charging means positioned at the top of the casing, and a chip discharge means positioned at the bottom of the casing, according to the invention, the apparatus is provided with an induction coil enclosing the casing for generating therein a rotating electromagnetic field, a ferromagnetic core secured inside the casing coaxially therewith and with the induction coil, a heated splitter of the lubricant-coolant secured in the casing under the ferromagnetic core, a portion of the casing above the induction coil having the form of a header for evacuating vapours of the lubricant-coolant, and a chip metering device secured coaxially with the casing between the chip charging means and header.
Advisably, the apparatus is provided with an oil trap connected to the header, and a condenser connected to the oil trap.
Desirably, the casing has a sleeve of a nonmagnetic material disposed at the portion of the casing enclosed by the induction coil.
Advantageously, the casing is provided with tuyeres for feeding a gas positioned at the casing under the heated splitter.
The heretofore described embodiment of the proposed apparatus for cleaning ferromagnetic chip from a lubricant-coolant ensures high chip cleaning quality allowing a subsequent chip utilization, high efficiency of the chip cleaning process, and protection of the environment against toxic discharge.